The subject NP which designates the place where an action happens or a state obtains requires the locative semantic role; the subject NP which designates the time of an action or a state requires the temporal semantic role:
1a. 伦敦多雾。
Lúndūn duō wù.
(London is foggy.)
1b. 我的帐篷睡得下三个人。
Wǒ de zhàngpeng shuì de xià sān gèrén.
(My tent can sleep three people.)
1c. 路上满是自行车和行人。
Lùshang mǎ nshì zìxíngchē hé xíngrén.
(The road is swarmed with bicycles and pedestrians.)
1d. 箱子里装满了书。
Xiāngzi lǐ zhuāngmǎn le shū.
(The box is packed with books.)
1e. 五月一号是劳动节。
Wǔyuè yīhào shì Láodòngjié.
(May the First is Labor Day.)
In the above sentences, all the subjects denote the location where the states described by the predicates apply. In (1c), for instance, the state of being full of bicycles and pedestrians obtains on the road. So the subject has the semantic role of location. The subject of (1e) designates the date on which it is Labor Day; hence the subject is assigned the semantic role of time.
[1] Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.